1. Field of the Invention
The present invention relates to an information processing apparatus, a calling method, and a communication system.
2. Description of the Related Art
A videoconference system is known as an example of a transmission system which is adapted to conduct a videoconference between two or more transmission terminals via a communication network, such as the Internet. In the videoconference system, a videoconference may be implemented by transmitting and receiving image data and voice data between the transmission terminals. A transmission terminal at a receiving end receives the image data and the voice data from a transmission terminal at a transmitting end, and an image of a user of the transmitting end is displayed on a display of the receiving terminal and voice sound of the user of the transmitting end is output by a speaker of the receiving terminal, so that the videoconference between the terminals is conducted.
In the videoconference system, while image data are continuously transmitted between the terminals, each of the terminals displays an image based on the image data received from other terminals in real time, and a user of each terminal may grasp the conditions of other locations where the other terminals are provided. Namely, a business operation may be carried out with a proper feeling of tension and a sense of togetherness because the users at different locations feel mutual presence via respective screens displayed on the terminals even when no conversation is exchanged between the users. Moreover, if the necessity arises and a user at a certain location starts conversation with another user at another location, it is possible to start a videoconference at any timing.
However, if the transmission system is configured so that each terminal continuously transmits image data even in the absence of conversation between the terminals, a first user of a first terminal may set the voice data from other terminals in a mute state or may set a volume control of the first terminal to a low level. In such cases, even if a second user of a second terminal intends to start conversation with the first user of the first terminal and calls out the first user loudly via the second terminal, the first user is likely to be unaware of the call from the second user.
To overcome the problem, it is proposed to send a request for starting conversation with the first user using a method other than the videoconferencing method from the second terminal to the first terminal. For example, see Japanese Laid-Open Patent Publication No. 2005-348185. Japanese Laid-Open Patent Publication No. 2005-348185 discloses a mobile terminal which is adapted to transmit an e-mail including content data to a mail address of a mobile terminal of a communication partner during a conversation with the communication partner.
However, it is required that the mobile terminal disclosed in Japanese Laid-Open Patent Publication No. 2005-348185 has an e-mail transmission/reception function as well as a call control function linked to a telephone line, and it is difficult to utilize such a mobile terminal technology for a transmission terminal having no such functions.